Brown Dwarfs as Galactic Chronometers

TL;DR

Brown dwarfs can serve as Galactic clocks due to their cooling over time, but precise age determination is challenging; this paper reviews five methods for estimating their ages and discusses their accuracy.

Contribution

The paper reviews five methods for determining brown dwarf ages, analyzing their applicability, limitations, and current empirical precision.

Findings

Five methods for age determination are reviewed.

Current empirical precisions of these methods are discussed.

Limitations in age estimation due to atmospheric and spectral complexities.

Abstract

Brown dwarfs are natural clocks, cooling and dimming over time due to insufficient core fusion. They are also numerous and present in nearly all Galactic environments, making them potentially useful chronometers for a variety of Galactic studies. For this potential to be realized, however, precise and accurate ages for individual sources are required, a prospect made difficult by the complex atmospheres and spectra of low-temperature brown dwarfs; degeneracy between mass, age and luminosity; and the lack of useful age trends in magnetic activity and rotation. In this contribution, I review five ways in which ages for brown dwarfs are uniquely determined, discuss their applicability and limitations, and give current empirical precisions.